/*
 * Copyright (c) 2012 copyright Gábor Heizer
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy,
 * modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software
 * is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
 * WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

package hu.my.bnf;

import hu.my.bnf.util.Properties;
import hu.my.bnf.validation.StringValidation;
import hu.my.bnf.validation.Validation;
import org.jetbrains.annotations.NotNull;
import org.jetbrains.annotations.Nullable;

import java.util.concurrent.ConcurrentHashMap;

/**
 * Extended BNF (Backus-Naur Form) - ISO14977.
 * <p />Examples:<pre>ee = {"A"}-, "E";</pre>
 */
public final class EBNF extends AbstractBNF {

//--------------------------------------------------------------------------------------------------------------------------------
// Fields
//--------------------------------------------------------------------------------------------------------------------------------

    /**
     * Cache limit.
     */
    public static final int MAP_LIMIT = Properties.getIntProperty(
            Constants.EBNF_MAP_LIMIT,
            Messages.RES_EBNF_MAP_LIMIT.getMessage()
    );
    /**
     * Cache.
     */
    private static final ConcurrentHashMap<String, EBNF> MAP = new ConcurrentHashMap<String, EBNF>();

    /**
     * Determines if a de-serialized file is compatible with this class.
     */
    private static final long serialVersionUID = 8237398811876003051L;

//--------------------------------------------------------------------------------------------------------------------------------
// Constructors
//--------------------------------------------------------------------------------------------------------------------------------

    /**
     * Constructor.
     *
     * @param urn            URN.
     * @param metaIdentifier Meta-Identifier.
     */
    private EBNF(@NotNull final String urn, @NotNull final String metaIdentifier) {
        super(urn, metaIdentifier);
    }

//--------------------------------------------------------------------------------------------------------------------------------
// Methods
//--------------------------------------------------------------------------------------------------------------------------------

    /**
     * Create EBNF Object.
     *
     * @param urn            URN.
     * @param metaIdentifier Meta-Identifier.
     * @return EBNF.
     */
    @NotNull
    public static EBNF getInstance(@Nullable final String urn, @Nullable final String metaIdentifier) {
        String key = StringValidation.getValidString(urn);

        EBNF ebnf = MAP.get(key);

        if (ebnf == null) {
            cleanMap();

            EBNF validEbnf = new EBNF(key, StringValidation.getValidString(metaIdentifier));
            ebnf = MAP.putIfAbsent(key, validEbnf);

            //This thread was the winner?
            ebnf = Validation.getIfNull(validEbnf, ebnf);
        }

        return ebnf;
    }

    /**
     * Clean cache.
     */
    private static void cleanMap() {
        if (MAP.size() > MAP_LIMIT) {
            MAP.clear();
        }
    }

    /**
     * Validates the EBNF.
     *
     * @return if the EBNF is valid.
     */
    @Override
    public boolean isValid() {
        return true;
    }
}
